Projection apparatus



Nov. 6, 1962 c. w. cARLsoN 3,062,063

PROJECTION APPARATUS Filed Nqv. l, 1960 2 Sheets-Sheet 1 I? 4/ will?) nwmrom Nov. 6, 1962 c. w. CARLSON 3,062,063

' PROJECTION APPARATUS Filed Nov. 1, 1960 2 Sheets-Sheet 2 United States Patent Ofifice 3,002,063 Patented Nov. 6, 1962 3,062,063 PROJECTION APPARATUS Charles W. Carlson, St. Charles, 111., assignor to Dukane Corporation, St. Charles, 111., a corporation of Dela- Filed Nov. 1, 1960, Ser. No. 66,574 Claims. (Cl. 74-125.5)

This invention relates to a projection apparatus and more particularly to a power means for advancing strip film a frame at a time through the film gate of a projector.

Power means for advancing strip film through the film gate of a projector have been well known and used. Such means are desirable for remote control as well as for automatic operation in response to signals reproduced from a record which may be used in conjunction with a strip film in a machine for combined projection and reproduction of sound or music. While many devices for advancing strip film are known and have been used, generally such devices have some drawbacks. Some devices are relatively expensive to manufacture and may be complicated. A serious objection to some devices is based upon the fact that the operation usually involves ob ectionable noise. Where the construction has been modilied to reduce the noise, other difficulties generally apear. p In a strip film projector, it is customary to have a pair of sprockets for driving the film through the film gate. The sprocket arrangement is such that a film frame is advanced by one-quarter of a turn of the sprockets. As a rule, the power drive between the motor and the frame advance means includes at least one part which is oscillatable over a fixed angle. This part is moved in one direction through its angular range for effecting a frame advance and is then returned by some bias means back to a starting position. Providing a biased type of frame drive makes for overall simplicity. Thus the ower drive can have fixed stops for defining the operating range. If the load turns in one direction only, then it is difficult to provide fixed stops and satisfactory operation over a fixed range.

It is desirable to use an electric motor as a source of energy for driving the frame advance means. Motors are cheap, efficient and can store considerable kinetic energy in the form of a rapidly rotating rotor. Where motors are used, it is necessary to use reducing gears.

In prior film drives it has been found undesirable to use non-metallic gears in those parts of the drive where one or more gears do not make a complete revolution. Such gears are desirable for quiet operation. It has been found that a non-metallic gear which oscillates over a fixed angle, as 90", concentrates the wear on the active gear teeth and particularly on the end teeth of the active gear portion. While such a non-metallic gear is quiet when new, rapid wear makes it undesirable to use.

The invention provides a helical spring type of clutch in a power drive between a gear and a load such as a frame advance means. This type of clutch permits the load on the gear to return to a normal biased position and reacts upon the gear in such fashion as to permit the gear to move freely in response to momentum. This action has the desirable result of eliminating any necessity for orienting the gear to any fixed starting position.

The construction embodying the present invention is characterized by simplicity as well as susceptibility of quick and silent operation. An advantage of the present construction resides in the fact that some parts may be manufactured of material which is softer than metal for the purpose of effecting quiet operation without concentrating the wear on any particular spot. Thus as an example, the construction embodying the present invention utilizes gears which may be made of fiber or plastic to provide quiet operation. By virtue of the new construction, no concentrated wear upon any portion of the gear results, and instead, the gear is used in such manner that actual wear is distributed in a random fashion over the entire extent of the gear. Consequently, a long useful life for the construction is provided.

Referring now to the drawings, FIGURE 1 is an ex ploded perspective view of one form of the present invention.

FlGURE 2 is a view partly in section illustrating the construction shown in FIGURE 1.

FIGURE 3 is a top view of "a modified form of the invention.

FIGURE 4 is an elevation of the modified form shown in FIGURE 3.

FIGURE 5 is an exploded perspective view of portions of a clutch.

Referring first to FIGURES l and 2, electric motor lltl has motor shaft 11 upon which is secured pinion 12. Electric motor 10 may be of any suitable type and is conveniently of the shaded pole induction type used in small devices. As a rule, motor 10 when energized by 60 cycle alternating current will have the shaft 11 normally rotating at about 1700 r.p.m. The exact speed, of course, will depend upon the load. Motor 10 may be supported in any suitable fashion not shown and is fixed relatively to plate 15. As a rule, plate 15 may be provided with clearance window 16 through which pinion 12 may be passed when mounting the motor and plate in proper relation to each other.

Plate 15 has rigidly supported therein one end of spindle l8. Rotatively disposed around spindle 18 is drive gear 20 having gear teeth around the entire periphery thereof. For convenience, only a portion of the gear surface is shown. However, it is understood that the gear teeth extend around the entire peripheral portion. Gear 20 has as part thereof or rigidly attached thereto hub member 22. Gear 20 may be of fiber or Bakelite or nylon or any other solid material other than metal which may be used for silencing the operation thereof. Hub 22 may be of the same material as gear 20 or may be of metal.

Hub 22 comprises one portion of a clutch. Disposed over spindle i3 is member 23 having generally cylindrical portion 24 which forms another portion of a clutch. The clutch element comprises helical coil spring 26. Coil spring 26 may be of wire having a rectangular cross section, although round wire may be used. The outside diameter of hub member 22 is large enough with reference to the inside diameter of coil spring 26, in its normal untensioned condition, so that several turns of the coil spring will always be snug about the outer surface of hub 22. The direction of the coils of spring 26 will be such that member 22. will tend to tighten the coils of spring 26 on itself when gear 20, as viewed from the lefthand end of the entire apparatus, is normally turned anticlockwise. The direction of winding of coil spring beginning from the end adjacent gear 20 is clockwise.

The outer diameter of hub member 24 is somewhat smaller than the inside diameter of coil spring 26 in its normal untensioned condition. Thus as an example, the clearance between the two may be of the order of one or two thousandths of an inch.

Hub 24 is part of member 23 which may form a part of the load of a device having a limited range of travel. When member 23 is part of a means for driving a film advance means, it is generally desirable to return member 23 to a starting position at the completion of an operating cycle. Accordingly, member 23 has rigidly attached thereto finger 29 extending outwardly. Finger 29 has hooked thereon one end of coil spring 29a, the

other end of which is attached to some stationary support not shown. Bolts 36 and 31 adjustably secured in plate by any simple means such as illustrated in the drawing determine the angular travel range of finger 29. Spring 29a normally biases finger 30 against stop bolt 30, from which position the motor will drive the finger to stop bolt 31.

As illustrated in the drawings, the complete motor drive between pinion 12 and the framing and film advance mechanism shown at the left on FIGURE 1 is provided with an additional clutch of the type previously described.

A simple coupling is provided between the two clutches, and as illustrated here, this coupling consists of hubs 32 and 33 connected together by flexible portion 34. Hub portion 32 is disposed in a recess in member 23 and is locked by one or more set screws 36. Similiarly, hub 33 is locked to a second normal driver portion 33 by set screw 39. Normal driver portion 33 is disposed over shaft 40, which for convenience may have substantially the same diameter as spindle i8. Cooperating with normal driver portion 58 is normal driven portion 41, the two portions cooperating with clutch element 43 consisting of a helical spring similar in all respects to helical spring 26. The relationship between parts 38 and 41 on the one hand and the inside diameter of coil spring 43 in its normal untensioned condition may generally be the same as in the clutch which has already been described. By controlling the direction of the winding of the coil spring, the other end of the coil spring can be made to grab. Thus for example, in the first clutch described, hub 24 is normally loose or free of the coil spring. It is clear, however, that the reversed relationship may be provided with the coil spring normally hugging hub 24 and free of hub 22. Similarly, in the second clutch just described, the end of the coil spring which normally hugs the drum can either be at the normal driving end or the normal driven end.

Normal driven hub 41 of the second clutch is rigidly coupled to an index member to be described. Thus hub 4-1 has reduced portion 45 over which fits sleeve 46. Sleeve 46 is rotatably locked to reduced portion 45 by set screw 47. Index member 46 is provided with four index slots 48 extending longitudinally of the member (parallel to the axis of the member) on the periphery thereof. These slots are symmetrically disposed around member 46 and cooperate with spring pressed ball 50 supported in rigid block 51 and pressed toward sleeve 46 by spring 52.

Index member 46 has sleeve end 54 adapted to receive spindle 56 forming part of a frame adjusting and advance mechanism. The detailed construction of the entire advance and framing mechanism is not important and may be varied. Thus as an example, the construction illustrated in United States Patent No. 2,607,262, issued on August 19, 1952, may be used. Generally speaking, such mechanisms have knob 6t) cooperating with sprockets 61 and 62 for providing a clutch connection between the sprockets on one hand and shaft 56 on the other hand. The mechanism disclosed in the above identified patent permits knob 6b to be pulled in one direction for disconnecting the clutch, knob 64 being rotatable to turn the sprockets to any desired position. Knob 60 may also be used independently of the clutch to manually advance the frame. Sprockets 61 and 62 cooperate with strip film 63, the strip film passing through a suitable film gate, not shown.

For convenience, take-up spindle 65 is provided. Spindle 65 has spring clip 66 into which the free end of film 63 may be caught. Spindle 65 is carried by bracket 67 and is rotatively coupled to pulley 68. Bracket 67 is carried by plate 71} forming part of the projection machine. Pulley 68 is coupled to knob 60 by flexible belt 71. Thus as the frame advance mechanism moves the film, take-up spindle 65 is turned to take up the film.

Slippage between belt 71 and the knob or pullley, or both, is relied upon for maintaining film 63 tight.

The operation of the device is as follows. Spring 29a biases finger 29 and hub 23 to the position illustrated in FIGURE 1. Assume now that motor 19 is energized. Pinion 12 will turn large gear 20 in the direction indicated by the arrow. In this direction coil spring 26 will tend to grip both clutch members and thus establish a driving connection between the two. The same action occurs in the second clutch involving members 38 and E1 and coil spring 43.

When the motor has driven the framing mechanism through the desired angle, in this specific case the motor 1% will stall due to finger 29 engaging bolt 31. As a rule, an automatic switch may be provided for deenergizing the motor at this time. As soon as the motor is dcenergized, spring 36 tends to return part 23 to its normal starting position. Looking at the drive from part 23 toward the frame advance means, it will be clear that the flow of power is still toward the frame advance but the direction of rotation is reversed. In such case, the second clutch including coil spring 4-3 Will release and permit part 38 to turn backward while leaving part 41 to remain stationary. The film frame advance means is now free to remain in its position while a portion of the power drive reverses its direction of travel.

Starting with part 23 and going toward motor 10, it will be noted that the direction of power flow has now been reversed as compared to normal driving and that the direction of rotation is also reversed. This will result in the first clutch including coil spring 26 remaining tight and permitting part 23 to turn backward and drive gear 20 and motor 10 backward. When finger 29 reaches its normal starting position, it stops. However, the gear drive and motor have momentum. The momentum of the gear drive and motor results in the clutch disconnecting parts 23 and 22 so that the motor and the gear drive can coast generally freely until they stop of their own accord. As a rule, hub 22 may turn backward through a substantial angle before stopping. The possibility that gear 20 will be turned back an even 360 to cause the same teeth to be used in a new cycle is remote. Even if that should happen, some added wear on some gear teeth would result in a change in the stopping position of the gear and motor. As a result, gear 20 will rarely, if ever, stop in the same position twice.

Instead of the clutch mechanism illustrated, any oneway drive may be used, providing that this is of the over-running type permitting generally free movement of the driven part. It is not necessary that the two clutches be similar in construction. However, the construction illustrated is simple, highly effective and quite efficient for the type of mechanism to be driven. The construction illustrated in FIGURES 1 and 2 may be considered as a direct drive in the sense that driving gear 20 and the load consisting of sprockets 61 and 62 are all coaxial. This construction may be modified, however, by providing a lever coupling as illustrated in FIGURES 3 and 4.

Referring now to FIGURES 3 to 5 inclusive, the electric motor and pinion and gear with the two clutch members and helical spring are the same as in FIGURES l and 2. However, clutch member 24 of FIGURE 3 is carried by part 23' having arm 23a.

The frame advance means illustrated in FIGURES 3 and 4 together with its clutch are also the same as in FIGURES 1 and 2. The normal driver portion of the second clutch has portion 38' provided with arm 38a, this being the same as part 23'. Connecting arms 23a and 38a is link 75. The system is biased to a normal start position by coil spring 76 extending between link 75 and bracket 77 carried by plate 15.

It is possible to utilize one stop for both starting and stopping in this construction. This is obtained by disposing arms 23a and 33a normally for starting so that each arm makes an angle with the vertical of half the operating range. Thus for example, where the entire travel of arm 38a is substantially 90, the starting and stopping positions of each of the arms should be 45 with respect to the vertical. By this arrangement, link 75 can cooperate with rubber stop 80 adjustably secured by a bolt and nuts in bracket 77.

The operation of this modification is similar to the operation of the construction illustrated in FIGURES 1 and 2 insofar as the clutches are concerned. As seen in FIGURE 4, spring 76 will normally pull link 75 down against rubber bumper 80. When the electric motor is energized, arm 23a is turned anti-clockwise as seen in FIGURE 4, first elevating link 75 above bumper 80 and then dropping it against the bumper to determine the stop position.

The construction illustrated in FIGURES 3 to 5 inclusive is advantageous where a different arrangement of motor and frame advance means is required as compared to the structure illustrated in FIGURES l and 2. It is understood that in the form illustrated in FIGURES 3 and 4, two separate stops similar to stops 30 and 31 in FIGURE 1 may be provided rather than combining the two stops into one.

In both forms of the invention, it should be noted that the index means will position the frame accurately in spite of some slight inaccuracies in the angular range of travel of the motor driven portions. Because of this, some slight differences between clutches can be tolerated.

What is claimed is:

l. A mechanical power drive comprising an electric motor including a rotor adapted to rotate in one direction only at high speed when the motor is energized, a pinion gear driven by said rotor, a relatively large gear meshing with said pinion gear to provide a speed reducing action, a pair of series connected overrunning type clutches for transmitting power in one direction only, a direct mechanical connection between said large gear and the free end of one clutch, a load having a limited angular range of normal travel connected to the free end of the other clutch, said two clutches transmitting power to the load from the electric motor rotor when rotating, means for biasing that part of the clutch system where the two clutches are series connected to a predetermined rotary starting position defining one end of a travel range, means for limiting the travel of the aforementioned part of the clutch system to define the other end of said travel range, said travel range being oriented so that upon motor energization the two series connected clutches will engage to turn the aforementioned part of the clutch system from its biased starting position to the other end of the travel range, the clutch system part travel range corresponding substantially to the load travel range, said large gear making less than one full turn for the travel of said clutch system part over its prescribed range, said motor rotor having substantial inertia so that after the power drive has operated in response to motor energization and when the motor has been deenergized and said clutch system part responds to its bias, said load will not be moved from its new position and instead the bias force will be directed backward through the large gear to the motor rotor to spin the rotor and gears and after said clutch part has reached its normal biased starting position, the rotating gears and rotor will continue to spin and coast and come to a stop at a random position which will differ in each operating cycle and distribute wear on the large gear over all the teeth.

2. A mechanical power drive comprising an electric motor including a rotor adapted to rotate in one direction only at high speed when the motor is energized, a pinion gear driven by said rotor, a relatively large gear meshing with said pinion gear to provide a speed reducing action, a pair of series connected overrunning type clutches for transmitting power in one direction only, a direct mechanical connection between said large gear and the free end of one clutch, a rotary load connected to the free end of the other clutch, said load including index means for determining a normal angular range of travel, said two clutches transmitting power to the load from the electric motor rotor when rotating, means for biasing that part of the clutch system where the two clutches are series connected to a predetermined rotary starting position defining one end of a travel range, means for limiting the travel of the aforementioned part of the clutch system to define the other end of said travel range, said travel range being oriented so that upon motor energization the two series connected clutches will engage to turn the aforementioned part of the clutch system from its biased starting position to the other end of the travel range, the clutch part travel range corresponding substantially to the normal load travel range, said large gear making less than one full turn for the travel of said clutch system part over its prescribed range, said motor rotor having substantial inertia so that after the power drive has operated in response to motor energization and when the motor has been deenergized and said clutch system part responds to its bias, said load will not be moved from its new position and instead the bias force will be directed backward through the large gear to the motor rotor to spin the rotor and gears and after said clutch part has reached its normal biased starting position, the rotating gears and rotor will continue to spin and coast and come to a stop at a random position which will differ in each operating cycle and distribute wear on the large gear over all the teeth.

3. A mechanical power drive comprising an electric motor including a rotor adapted to rotate in one direction only at high speed when the motor is energized, a pinion gear driven by said rotor, a relatively large gear meshing with said pinion gear to provide a speed reducing action, a pair of series connected overrunning type clutches for transmitting power in one direction only, each clutch having one helical spring and at least one hub to be gripped by the end coils when the clutch is active, a direct mechanical connection between said large gear and the free end of one clutch, a load having a limited angular range of travel connected to the free end of the other clutch, said two clutches transmitting power to the load from the electric motor rotor when rotating, means for biasing that part of the clutch system where the two clutches are series connected to a predetermined rotary starting position defining one end of a travel range, means for limiting the travel of the aforementioned part of the clutch system to define the other end of said travel range, said travel range being oriented so that upon motor energization the two series connected clutches will engage to turn the aforementioned part of the clutch system from its biased starting position to the other end of the travel range, the clutch system part travel range corresponding substantially to the load travel range, said large gear making less than one full turn for the travel of said clutch system part over its prescribed range, said motor rotor having substantial inertia so that after the power drive has operated in response to motor energization and when the motor has been deenergized and said clutch system part responds to its bias, said load will not be moved from its new position and instead the bias force will be directed backward through the large gear to the motor rotor to spin the rotor and gears and after said clutch part has reached its normal biased starting position, the rotating gears and rotor will continue to spin and coast and come to a stop at a random position which will differ in each operating cycle and distribute wear on the large gear over all the teeth.

4. The construction according to claim 3 wherein said load includes index means for determining the normal angular range of travel.

5. A mechanical power drive comprising an electric motor including a rotor adapted to rotate in one direction only at high speed when the motor is energized, a.

pinion gear driven by said rotor, a relatively large gear meshing with said pinion gear to provide a speed reducmg action, a pair of series connected overrunning type clutches for transmitting power in one direction only, a direct mechanical connection between said large gear and the free end of one clutch, a film frame advance means for a projector, said advance means including index means for determining the travel to move one film frame, said two clutches transmitting power to the film frame advance means from the electric motor rotor when rotating, means for biasing that part of the clutch system where the two clutches are series connected to a predetermined rotary starting position defining one end of a travel range, means for limiting the travel of the aforementioned part of the clutch system to define the other end of said travel range, said travel range being oriented so that upon motor energization the two series connected clutches will engage to turn the aforementioned part of the clutch system from its biased starting position to the other end of the travel range, the clutch part travel range corresponding substantially to the frame advance range, said large gear making less than one full turn for the travel of said clutch system part over its prescribed range, said motor rotor having substantial inertia so that after the power drive has operated in response to motor energization and when the motor has been deenergized and said clutch system part responds to its bias, said frame advance means will not be moved from its new position and instead the bias force will be directed backward through the large gear to the motor rotor to spin the rotor and gears and after said clutch part has reached its normal biased starting position, the rotating gears and rotor will continue to spin and coast and come to a stop at a random position which will difier in each operating cycle and distribute wear on the large gear over all the teeth.

6. A mechanical power drive comprising an electric motor including a rotor adapted to rotate in one direction only at high speed when the motor is energized, a pinion gear driven by said rotor, a relatively large gear meshing with said pinion gear to provide a speed reducing action, four separate cylindrical hubs in alinement with the axis of said large gear, helical springs disposed on said hubs to provide a pair of series connected overrunning type clutches for transmitting power in one direction only, a direct mechanical connection between said large gear and one hub forming the free end of one clutch, index means having a limited angular range of normal travel connected to a hub forming the free end of the other clutch, said two clutches transmitting power to the index means from the electric motor rotor when rotating, means for biasing that part of the clutch system where the two clutches are series connected to a predetermined rotary starting position defining one end of a travel range, means for limiting the travel of the aforementioned part of the clutch system to define the other end of said travel range, said travel range being oriented so that upon motor energization the two series connected clutches will engage to turn the aforementioned part of the clutch system from its biased starting position to the other end of the travel range, the clutch system part travel range corresponding substantially to an index step, said large gear making less than one full turn for the travel of said clutch system part over its prescribed range, said motor rotor having substantial inertia so that after the power drive has operated in response to motor energization and when the motor has been deenergized and said clutch system part responds to its bias, said load will not be moved from its new position and instead the bias force will be directed backward through the large gear to the motor rotor to spin the rotor and gears and after said clutch part "has reached its normal biased starting position, the rotating gears and rotor will continue to spin and coast and come to a stop at a random position which will differ in each operating cycle and distribute wear on the large gear over all the teeth and a load coupled to said index means to be turned by said motor over an index step.

7. The construction according to claim 6 wherein said load consists of a frame advance means on a projector for use with film.

8. A mechanical power drive comprising an electric motor including a rotor adapted to rotate in one direction only at high speed when the motor is energized, a pinion gear driven by said rotor, a relatively large gear meshing with said pinion gear to provide a speed reducing action, a pair of overrunning type clutches, means including a link for providing a series connection between said clutches for transmitting power through said clutches in one direction only, a direct mechanical connection between said large gear and the free end of one clutch, a rotary load connected to the free end of the other clutch, said load including index means for determining a normal angular range of travel, said two clutches transmitting power to the load from the electric motor rotor when rotating, means for biasing the clutch link to a predetermined starting position defining one end of a travel range, means for limiting the travel of the link to define the other end of said travel range, said travel range being oriented so that upon motor energization the two series connected clutches will engage to move the link from its biased starting position to the other end of the travel range, the link travel range corresponding substantially to the normal load travel range, said large gear making less than one full turn for the travel of said link over its prescribed range, said motor rotor having substantial inertia so that after the power drive has operated in response to motor energization and when the motor has been deenergized and said link responds to its bias, said load will not be moved from it new position and instead the bias force will be directed backward through the large gear to the motor rotor to spin the rotor and gears and after said link has reached its normal biased starting position, the rotating gears and rotor will continue to spin and coast and come to a stop at a random position which will difier in each operating cycle and distribute wear on the large gear over all the teeth.

9. The construction according to claim 8 wherein said load comprises a frame advance means forming part of a film projector.

10. The construction according to claim 9 wherein the range defining means for the link comprises a stop for limiting the lateral movement of said link, said link movin laterally and longitudinally during operation of the drive.

References Cited in the file of this patent UNITED STATES PATENTS 1,891,101 Le Count -1 Dec. 13, 1932 2,064,452 Watson Dec. 15, 1936 2,622,450 Gorske et al Dec. 23, 1952 2,626,029 Gutterman I an. 20, 1953 FOREIGN PATENTS 1,010,465 France Mar. 26, 1952 

